The storage medium for a disc drive is a flat, circular disc capable of retaining localized magnetic fields. The data that are stored upon the disc find physical representation through these localized magnetic fields. The data are arranged on the disc in concentric, circular paths known as tracks.
The localized magnetic fields can be detected by a magnetically sensitive element (“a read element”) when they are brought in close proximity to the element. During operation the disc continually rotates, meaning that for each rotation, a read element fixed a given radius from the center of the disc would encounter every localized magnetic field along a given track. Altering the radial coordinate of the read element allows the head to read or write data along a different track.
The magnetically sensitive element responsible for reading the localized magnetic fields is located in a device known as a “slider” (the write element is also housed in the slider). A slider is a device attached to a gimbal tongue, which is, in turn, attached at a load point to the distal end of an actuator arm. The slider has an air bearing surface that is shaped so as to cause the slider to literally float at a small distance over the surface of the disc, when the disc is rotating. For the read element to properly detect the localized magnetic fields as they pass beneath it, the read element must be maintained at a proper height above the surface of the disc. If the read element floats at a distance that is too great, the read element may not detect each field as it passes beneath the element. On the other hand, if the read element is too close to the disc, the read element may become overly saturated.
One factor that affects the distance between a read element and the surface of a disc is the tendency of a slider to warp over time. As a slider warps, the read element (which is a part of the slider) is moved either toward or away from the edge of the slider that is to float above the disc. Consequently, even if the slider were to float at the same distance from disc as it did before it became warped, the read element, itself, would be either closer or further from the disc. In short, warping of the slider affects the position of the read element relative to the geometry of the slider.
As is made evident from the foregoing discussion, there exists a need for a scheme by which slider warpage may be minimized. By minimizing slider warpage, a disc may be read from and written to with increased reliability.